The present invention relates to a method of improving sound quality for performing improvement against bad influence due to uncomfortable sounds such as a motor driving sound during operation, an impulsive sound due to operation of a clutch or a solenoid, or a sound produced during paper conveyance, and also to an image formation apparatus using the same.
In recent years, there has been a growing interest in a noise problem from a viewpoint of being friendly to the environment. The office environment has also the same noise problem. Accordingly, there are many requests to solve the noise problem in OA equipment used in offices. Therefore, silencing of OA equipment has been progressing and a quite higher level of silencing can be achieved as compared to the conventional technology.
As a concrete example of silencing, there is one that generates a masking sound corresponding to a frequency band of noise so as to make the noise unobtrusive as described in Japanese Patent Application Laid-Open No. 09-193506. In this example, a sound is not eliminated by eliminating a noise source itself but by adding a masking sound to the sound. Therefore, a noise level sometimes increase, which may be heard obtrusive. Further, a masking sound generating mechanism is required, which may cause a device to be upsized.
Some examples of focusing on sound quality and evaluating it are proposed (e.g., Japanese Patent Application Laid-Open (JPA) No. 10-232163, JPA No. 10-253440, JPA No. 10-253442, JPA No. 10-267742, and JPA No. 10-267743).
A sound power level (ISO 7779) is generally used as a method of evaluating noise in the OA equipment.
However, since the sound power level is a value of sound energy produced from office equipment such as a copier or a printer, a correlation between the value and a subjective uncomfortable feeling of a human against noise may not be obtained accurately. For example, when you listen to sounds having the same sound power level by comparing one to another, you may find that there is a difference in discomfort between the sounds. Some of the sounds having a small value of the sound power level is sometimes very annoying. Therefore, in order to improve the office environment in the future, it is required to not only evaluate sounds of the OA equipment based on the sound power levels and reduce them but also evaluate and improve their sound quality. In order to evaluate and improve sound quality, it is necessary to perform quantitative measurement of sound quality to ascertain the present situation and measure how much the sound quality is improved after improvement is applied as compared to the sound quality before the improvement.
In general, the sound quality is not a physical quantity, so that quantitative measurement cannot be performed. Accordingly, it is also difficult to set a target value in the current situation.
When the sound quality is evaluated by a human, only qualitative expressions are given such as xe2x80x9csound quality has been improved a littlexe2x80x9d or xe2x80x9cit has been improved quite a lotxe2x80x9d. Further, there is an individual difference. Therefore, evaluation may be different depending on individuals, or it may be difficult to determine whether an obtained result can be generalized.
In order to learn whether measures actually taken for evaluation of sound quality have been truly effective or how much the measures have been effective, the quality of the sound has to be expressed quantitatively based on physical characteristics. If not, it is impossible to objectively evaluate the sound quality.
There are psychological sound parameters as physical quantities used for evaluation of sound quality. Typical ones are as follows (inside the parentheses: units). (See, e.g., xe2x80x9cDesign and System""s Conference ""97: With the aim of innovative jump of design and system toward the 21 centuryxe2x80x9d Japanese Society of Mechanical Engineers, Nov. 10, 11, 1997, Paper No. 089B on Session xe2x80x9cSound, Vibration and Design, Color and Design (1)xe2x80x9d)
Loudness (sone)
Sharpness (acum): Relative distribution of high frequency components
Tonality (tu): Articulatory property, content of a pure sound component
Roughness (asper): Feeling of sound roughness
Fluctuation strength (vacil): A sort of whine
In addition to these parameters, equipment capable of measuring a psychological sound parameter such as Impulsiveness (iu) has appeared on the market.
The uncomfortable feeling will increase as the values of the parameters increase. Of the parameters, only the loudness is standardized in ISO 532B. With regard to the other parameters, programs and calculating methods are different depending on specific studies by makers of measuring instrument although their basic ideas are the same. Therefore, naturally, measured values are slightly different depending on the makers.
By expending efforts to reduce all of these psychological sound parameters, the sound quality will certainly be improved.
However, taking measures against all the parameters requires enormous efforts.
Noise produced from the OA equipment such as a copier or a printer includes noise with various types of tones due to complexity of its mechanism. For example, oppressive sounds of low frequencies, high-pitched sounds of high frequencies, or impulsively produced sounds are produced from a plurality of sound sources such as the motor, paper and solenoid while changing over time. A human analyzes totally these sounds to determine whether they are uncomfortable sounds, and, during this time, it is considered that the determination is given by applying a weight to any part that is particularly related to discomfort. That is, there are some of psychological sound parameters that may largely affect discomfort and some that may not much affect discomfort. These sound types are different depending on tones of machines. For example, in a printer that operates at a high speed and produces a large number of impulsive sounds, the impulsive sounds are felt the most uncomfortable. While, in a desktop printer that operates at a low speed and comparatively quietly, charging sounds during AC charging are felt the most uncomfortable because the impulsive sounds are not much produced. The sound sources that make us feel uncomfortable are different as explained in the above cases. Therefore, the sound sources whose sound quality is to be improved may be different in a low-speed machine and a high-speed machine. Based on this fact, less efforts will be expended by finding out a sound source to be largely effective in improvement against discomfort and its psychological sound parameters, and efficiently improving its sound quality through reduction in values of the psychological sound parameters by means of countermeasures against the uncomfortable sound source and countermeasures against its transmission path.
As a result, it becomes possible to objectively evaluate the sound quality by combining psychological sound parameters largely effective in improvement against discomfort, applying each weight to the parameters, expressing them by an evaluating equation for sound quality, and calculating subjective evaluation values for discomfort. Thus, the sound quality can be improved. Further, it is determined which values of the subjective evaluation values for discomfort are to be set so that the discomfort will disappear. By providing an apparatus whose sound quality has been improved so as to be less than the values, the problem on noise within offices will be solved.
It is an object of this invention to enable reduction of uncomfortable sounds by improving their sound quality. More specifically, it is an object of this invention to provide a sound quality improving method capable of loosening a psychological uncomfortable feeling.
Another object of this invention is to provide a sound quality improving method capable of more effectively loosening a psychological uncomfortable feeling.
A further object of this invention is to provide a sound quality improving method capable of loosening an uncomfortable feeling by reducing a sound produced during paper conveyance in an image forming device.
A still further object of this invention is to provide a sound quality improving method capable of loosening an uncomfortable feeling by reducing an impulsive sound due to metal in an image forming device.
A still further object of this invention is to provide a sound quality improving method capable of loosening an uncomfortable feeling by reducing noise produced from a drive system of a paper feeding unit in an image forming device.
In order to solve the problem on such uncomfortable sounds, a still further object of this invention is to provide an image formation apparatus capable of loosening a psychological uncomfortable feeling by improving a source of uncomfortable sound produced during operation at a comparatively higher speed.
A still further object of this invention is to provide an image formation apparatus capable of loosening a psychological uncomfortable feeling by selectively combining uncomfortable sound sources so as to reduce the sounds.
A still further object of this invention is to provide an image formation apparatus capable of loosening a psychological uncomfortable feeling by specifying calculation of psychological sound parameters by a limited condition.
One aspect of this invention is the method of improving the quality of sounds produced from a device provided with a mechanical drive mechanism and the like. By using either one of or both of units for suppressing noise of a noise source produced in the device and of its transmission path, a discomfort index S of a sound obtained by inputting a value of loudness and a value of sharpness of psychological sound parameters obtained from a sound at a position apart by 1 meter from the exterior of the device into the following equation (a):
S=0.01024269xc3x97(loudness value)2+0.30996744xc3x97(sharpness value)xe2x88x922.1386517xe2x80x83xe2x80x83(a)
will satisfy the following condition (b):
S less than xe2x88x920.3555xe2x80x83xe2x80x83(b)
Further, the obtained discomfort index S further satisfies the following condition (c):
xe2x80x83S less than xe2x88x920.6296xe2x80x83xe2x80x83(c)
Another aspect of this invention is the image formation apparatus to which the sound quality improving method according to the invention is applied. The mechanical drive mechanism includes a paper conveying unit and a drive transmitting unit, and a sound produced from the paper conveying unit is reduced to satisfy the condition (b) or (c).
Further, the image formation apparatus uses a unit that reduces a sliding sound produced between paper and a guiding member for the paper as the sound produced from the paper conveying unit.
Further, in the image formation apparatus, the paper conveying unit has a guiding unit for paper, which is formed with a flexible sheet, and an edge part of its surface contacting the paper is bent.
Further, in the image formation apparatus, a metal-impulsive sound is reduced to satisfy the condition (b) or (c).
Further, the image formation apparatus further comprises paper conveying units in a plurality of stages which become a source where the metal-impulsive sound is produced. The paper conveying units have electromagnetic clutches for the number of stages, and, of the electromagnetic clutches, only an electromagnetic clutch of the paper conveying unit in a state of being ready to convey paper is operated.
Further, in the image formation apparatus, a sound produced from a drive system of the paper conveying unit is reduced to satisfy the condition (b) or (c).
Further, in the image formation apparatus, air-borne sound is insulated from the drive system.
Further, in the image formation apparatus, the mechanical drive mechanism has a developing unit, and a sound from the developing unit is reduced to satisfy the condition (b) or (c).
Further, in the image formation apparatus, the developing unit has a developing member and a developing member driving unit that drives the developing member. The developing member driving unit has a drive transmitting unit for transmitting a drive force to the developing member, and a reference with respect to positioning for transmitting a driving force between the developing member driving unit and the developing member and a reference with respect to positioning for mounting both of the unit and member are made coincide with each other.
Further, the image formation apparatus satisfies the condition (b) or (c) by using either one of or both of suppressing units. One of the units absorbs noise from a noise source itself to suppress the noise by selectively combining noises produced from sound sources inside the apparatus, and the other one is disposed on the transmission path of the noise.
Further, in the image formation apparatus, the loudness value and sharpness value are obtained by collecting sounds produced from the image formation apparatus with a sound measuring device HSMIII manufactured by Head Acoustics and analyzing the sounds with a Binaural Analysis System BAS manufactured by Head Acoustics, and the discomfort index S satisfies the condition (b):
S less than xe2x88x920.3555xe2x80x83xe2x80x83(b)
or the condition (c):
S less than xe2x88x920.6296xe2x80x83xe2x80x83(c)
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.